The objective of this study is to evaluate the recurrence of white and/or red oral soft tissue lesions or changes in the neoplastic status of these lesions in relation to molecular events. Persons with white and or red oral mucosal lesions seen at six Veterans Affairs hospitals will be selected for the study. Study subjects will undergo a biopsy of all suspect oral lesions, provide information about tobacco, alcohol intake, and other habits and will be re-examined every four months for two years and re-biopsied as appropriate. The biopsy material will be analyzed for the presence or activity of certain molecules thought to be associated with the malignant phenotype including p53-dependent growth suppressors, pRb-dependent growth control factors, growth factor receptor-modulated pathways, and viral agents. Statistical analysis will determine associations between molecular markers from the oral lesions and the lesions' histopathology and will examine how environmental, behavioral, and sociodemographic factors influence these associations. If molecules indicative of early transformation can be identified, they may be used to identify persons who should be monitored most closely for the development of oral cancer and to recognize oral cancers at the earliest, most treatable stage.